Rare Rabbit
If you in the Pandemonium, a FMV sequence will start with the rabbit. When it ends, the rabbit is in his hole. Enable the noclip code. Run in the wall to see a piece of code instead of the rabbit.

Guard's Voice
When the Alice's "guard" talks to you, run away to hear his voice better. When running away, he stops talking. Quickly run back. The "guard" will not be able to talk anymore.

Surviving Cheshire Cat
Before you fight the Queen Of Hearts at the end of the game, the Cheshire Cat will die. Press C while you fight the Queen and he will appear again, as if he were alive.